Techniques and assemblies for joining components

ABSTRACT

The disclosure describes example techniques and assemblies for joining a first component and a second component. The techniques may include positioning the first and second component adjacent to each other to define a joint region between adjacent portions of the first component and the second component, the joint region being coated with an adhesion resistant coating. The techniques may also include positioning a braze material in the joint region, heating the braze material to form an at least softened material, and cooling the at least softened material to form a mechanical interlock including the braze material in the joint region joining the first and second components. The braze material does not metallurgically bond to the joint surface.

This application is a continuation of U.S. Pat. Application No.16/294,415 filed on Mar. 6, 2019, which claims the benefit of U.S.Provisional Pat. Application No. 62/640,349, filed Mar. 8, 2018, theentire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure generally relates to techniques and assembliesfor joining components.

BACKGROUND

Casting may be used to form metal or alloy components. However, castingrelatively large articles or articles having a relatively complexgeometry in a single operation may be difficult, or result in deviationof a cast article from specifications or tolerance. When formingarticles from superalloys including a single crystal, casting may bedifficult, leading to relatively high rejection rates due to defects inthe cast article. For example, nozzle guide vanes for gas turbineengines may be cast as a single crystal, and this may restrict designcomplexity of the nozzle guide vanes. Instead of casting or otherwiseforming large or complex articles as a single piece or component, sucharticles may be cast or otherwise fabricated in the form of separatecomponents, which may be joined to form an assembly.

SUMMARY

The disclosure describes example assemblies and techniques for joiningcomponents, for example, metal or alloy components or ceramic-basedcomponents.

In some examples, the disclosure describes an example techniqueincluding positioning a first component and a second component adjacentto each other to define a joint region between adjacent portions of thefirst component and the second component. The joint region defines ajoint surface. The example technique further includes positioning abraze in the joint region. An adhesion resistant material presentbetween the braze material and the joint surface. The adhesion resistantmaterial is configured to resist adherence of the braze material to thejoint surface. The example technique further includes heating the brazematerial to a processing temperature to form an at least softenedmaterial in the joint region. The example technique further includescooling the at least softened material to form a mechanical interlockincluding the braze material in the joint region joining the first andsecond components. The braze material does not metallurgically bond tothe joint surface.

In some examples, the disclosure describes an example assembly includinga first component and a second component. The first component and secondcomponent are positioned adjacent to each other to define a joint regionbetween adjacent portions of the first component and the secondcomponent. The joint region defines a joint surface. The exampleassembly includes a mechanical interlock including braze materialdisposed in the joint region. The assembly also include an adhesionresistant material between the braze material and the joint surface. Theadhesion resistant material is configured to resist adherence of thebraze material to the joint surface. The braze material is configured toform an at least softened material in the joint region in response toheating the braze material to a processing temperature. The at leastsoftened material is configured to form the mechanical interlock in thejoint region mechanically joining the first and second components inresponse to cooling. The braze material is not metallurgically bonded tothe first component or the second component.

The details of one or more examples are set forth in the accompanyingdrawings and the description below. Other features, objects, andadvantages will be apparent from the description and drawings, and fromthe claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a conceptual and schematic diagram illustrating an explodedview of an example assembly for joining a first component and a secondcomponent using a braze material to form a mechanical interlock.

FIG. 1B is a conceptual and schematic diagram illustrating a partialview of an example system including the assembly of FIG. 1A in afurnace.

FIG. 1C is a conceptual and schematic diagram illustrating a partialsectional and exploded view of region A of the system of FIG. 1B.

FIG. 2 is a flow diagram illustrating an example technique formechanically joining components including using a braze material withoutmetallurgically bonding the components.

FIG. 3A is a conceptual and schematic diagram illustrating an explodedcross-sectional view of an example assembly including components and amechanical interlock including a braze material between components.

FIG. 3B is a conceptual and schematic diagram illustrating an assembledcross-sectional view of the example assembly of FIG. 3A.

FIG. 3C is a conceptual and schematic diagram illustrating a partialcross-sectional view of region C of the assembly of FIG. 3B.

FIG. 4 is a conceptual and schematic diagram illustrating a partialcross-sectional view of an example assembly including components anddefining a joint region for forming a mechanical interlock including abraze material.

FIG. 5 is a conceptual and schematic diagram illustrating a partialcross-sectional view of an example assembly including components andbraze paste that forms a mechanical interlock.

FIG. 6 is a conceptual and schematic diagram illustrating a partialcross-sectional view of an example assembly including components andbraze putty that forms a mechanical interlock.

FIG. 7 is a conceptual and schematic diagram illustrating a partialcross-sectional view of an example assembly including components andpre-sintered preform strips including braze material that form amechanical interlock.

FIG. 8 is a conceptual and schematic diagram illustrating a partialcross-sectional view of an example assembly including components andpre-molded pre-sintered preform strips including braze material thatform a mechanical interlock.

FIG. 9A is a conceptual and schematic diagram illustrating a partialsectional and exploded view of a region similar to region A of thesystem of FIG. 1B.

FIG. 9B is a conceptual and schematic diagram illustrating a partialsectional and exploded view of a region similar to region A of thesystem of FIG. 1B.

DETAILED DESCRIPTION

The disclosure describes assemblies, systems, articles, and techniquesfor joining a first component and a second component using a brazematerial that does not metallurgically bond the first component to thesecond component. The first component and the second component define ajoint region defining a joint surface. An adhesion resistant material ispresent between the joint surface and the braze material and isconfigured to resist adherence of the braze material to the jointsurface. At least one of the first or the second component may include ametal, an alloy, or a ceramic-based structure, for example, a ceramicmatrix composite.

In some example techniques, the braze material is heated to a processingtemperature to form an at least softened material, which may flow,occupy, or otherwise at least partially conform to the joint region(e.g., may conform to or nearly conform to at least a portion of thejoint region). The at least softened material may cool to form amechanical interlock in the joint region, restraining the firstcomponent relative to the second component. In some examples, themechanical interlock may at least partially surround one or both of thefirst component or the second component. The mechanical may mechanicallysecure the first component relative to the second component. The firstor second components may include components or a gas turbine engine, forexample, a high-pressure nozzle guide vane and shroud. In some example,the components may include any components benefitting from a closefitting (relatively low leakage) structural connection inhigh-temperature operating conditions.

While techniques such as bi-casting may be used to produce an integrallyformed metallic joint or “clip” to structurally connect components,bi-casting may require a casting foundry, including, for example,separate furnace preheat and furnace (liquid metal) pouring operationswith elaborate tooling (while needing close monitoring and control invarious stages of the process). In order to integrally form a bi-castjoint or clip, a metal or alloy may need to be fully molten or liquidand superheated to a temperature well above the melting point ofcomponents being joined. Moreover, any significant leakage of moltenmetal or alloy during the bi-casting process may affect the integrity ofcomponents being joined or of surrounding furnace tooling, which may becostly and difficult to replace.

In contrast, example techniques and assemblies according to thedisclosure may be deployed using treatment temperatures and durationsthat may substantially maintain the integrity of the components beingjoined and tooling or support components used for joining thecomponents. Some example techniques and assemblies according to thedisclosure may result in a relatively low leakage structural connectionbetween components operating in high temperature environments. In someexamples, a plurality of pairs of components may be joined at the sametime using a batch process, in contrast with a bi-casting process inwhich a single pair of first and second components and is processed at atime and processing multiple pairs of components requires multipleprocessings. In some examples, the braze material may include wide gapbraze alloy, a pre-sintered preform (PSP) or another composition havingpredetermined ratios of braze alloy to superalloy powder as describedelsewhere in the disclosure.

Because the braze materials described herein may possess mechanical andchemical properties (e.g., mechanical strength and high temperatureoxidation resistance) that make the material suitable for use in hightemperature oxidative environments, the braze materials may facilitatemanufacture of articles for high temperature mechanical systems inmultiple components, which are then joined using the braze materials.This may reduce cost of manufacture due to lower defect levels in thecomponents, facilitate more complex geometry, or the like. In someexamples, the braze materials including a PSP also may provideadvantages compared to powder braze materials. For example, the PSPmaterials may result in reduced porosity in joints compared to jointsformed using a braze powder, which may improve mechanical properties ofthe braze joint. Further, the PSP materials may be easier to position inthe joint region and result in a more uniform joint.

The adhesion-resistant material is selected to resist the formation of ametallurgical bond between the mechanical interlock formed by the brazematerial and the joint surfaces. For example, the adhesion resistantmaterial may include a coating that may act as a leave-in-place“stop-off”, substantially preventing the formation of a metallurgicalbond, while avoiding or substantially preventing introducing a gap (ascontrasted with a stop-off removed after application). As anotherexample, the adhesion resistant material may include a superalloy foilor a superalloy powder present between the braze material and the jointsurfaces. The superalloy foil or superalloy powder may be selected tohave a melting point above the processing temperature to which the brazematerial is heated, such that the superalloy foil or superalloy powderdoes not melt during processing of the braze material to form themechanical interlock. Avoiding the formation of a metallurgical bond mayhelp maintain the integrity of the mechanical interlock and the jointregion, for example, in response to mechanical and thermal stressesapplied to the components and the mechanical interlock, by allowingconstrained relaxation of the components and the mechanical interlock.

Additionally, in some examples, the superalloy foil or superalloy powdermay have relatively lower levels of melting point depressants, such asboron or silicon, than the braze material. The superalloy foil orsuperalloy powder thus may act as a melting point depressant sink intowhich the melting point depressants may diffuse from the braze materialduring the processing of the braze material. This may result in themelting point of the braze material being raised to provide improve hightemperature capabilities to the resulting joint.

FIG. 1A is a conceptual and schematic diagram illustrating an explodedview of an example assembly 10 for joining a first component 12 a and asecond component 12 b using a braze material 14 to form a mechanicalinterlock. At least one of first or second components 12 a or 12 b mayinclude metal, alloy, or a ceramic-based structure, for example, aceramic-matrix composite. In some examples, first and second components12 a and 12 b (also referred to as “components 12 a and 12 b") may bejoined to form an article or a portion of an article that is part of ahigh temperature mechanical system. For example, components 12 a and 12b may be joined to form an article or a portion of nozzle guide vane(NGV) that is used in a high pressure or intermediate pressure stage ina gas turbine engine. In other examples, the article may include anothercomponent of a high temperature mechanical system, such as anothercomponent of a gas turbine engine. For example, the article may includea gas turbine engine blade alone or with a blade shroud, gas turbineengine vane, blade track, combustor liner, or the like.

Each of components 12 a and 12 b may include a metal or alloy, or aceramic. In some examples, components 12 a and 12 b includesubstantially the same (e.g., the same or nearly the same) metal oralloy. In other examples, components 12 a and 12 b include differentmetals or alloys. In some examples, one or both of components 12 a and12 b may include a Ni-, Co-, or Fe-based superalloy, or the like. Thesuperalloy may include other additive elements to alter its mechanicaland chemical properties, such as toughness, hardness, temperaturestability, corrosion resistance, oxidation resistance, and the like. Anyuseful superalloy may be utilized in first or second components 12 a or12 b, including, for example, Ni-based alloys available fromMartin-Marietta Corp., Bethesda, MD, under the trade designationMAR-M246, MAR-M247; Ni-based alloys available from Cannon-MuskegonCorp., Muskegon, MI, under the trade designations CMSX-3, CMSX-4,CMSX-10, and CM-186; Co-based alloys available from Martin-MariettaCorp., Bethesda, MD, under the trade designation MAR-M509; and the like.The compositions of CMSX-3 and CMSX-4 are shown below in Table 1.

Table 1 CMSX-3 (wt. %) CMSX-4 (wt. %) Cr 8 6.5 Al 5.6 5.6 Ti 1 1 Co 5 10W 8 6 Mo 0.6 0.6 Ta 6 6 Hf 0.1 0.1 Re 3 Ni Balance Balance

One or both of components 12 a and 12 b may be made using at least oneof casting, forging, powder metallurgy, molding, or additivemanufacturing. In some examples, components 12 a and 12 b are made usingthe same process, while in other examples, components 12 a and 12 b aremade using different processes.

In some examples, one or both of components 12 a or 12 b may include aceramic or ceramic-matrix composite (CMC). The ceramic or CMC mayinclude any useful ceramic material, including, for example, siliconcarbide, silicon nitride, alumina, silica, and the like. The CMC mayfurther include any desired filler material, and the filler material mayinclude a continuous reinforcement or a discontinuous reinforcement. Forexample, the filler material may include discontinuous whiskers,platelets, or particulates. As another example, the filler material mayinclude a continuous monofilament or multifilament weave. In someexamples, the CMC may include a SiC/SiC CMC, or an oxide/oxide CMC. Forexample, an SiC/SiC or oxide/oxide CMC component may be joined to ametal or alloy component or another SiC/SiC or oxide/oxide CMCcomponent.

Although FIG. 1A illustrates components 12 a and 12 b as each defining asimple, substantially curvilinear geometry, in other examples, one orboth of first or second components 12 a or 12 b may define a morecomplex geometry, including simple or complex curves, overhangs,undercuts, internal cavities, or the like.

First component 12 a defines at least one joining region 16 a defining ajoint surface 18 a. Similarly, second component 12 b defines at leastone joining region 16 b defining a joint surface 18 b. In some examples,first and second joint surfaces 18 a and 18 b (also referred to as“joint surfaces 18 a and 18 b") may define complementary shapes. FIG. 1Aillustrates joint surfaces 18 a and 18 b as defining substantially flatsurfaces. In other examples, joint surfaces 18 a and 18 b may defineother, more complex shapes, including, for example, simple or complexcurves, overhangs, undercuts, apertures, annuluses, or the like.

Components 12 a and 12 b are positionable such that joining regions 16 aand 16 b are adjacent to each other and define a joint region (not shownin FIG. 1A). The joint region may include any kind of simple or complexjoint, including, for example, at least one of a bridle joint, a buttjoint, a miter joint, a dado joint, a groove joint, a tongue and groovejoint, a mortise and tenon joint, a birdsmouth joint, a halved joint, abiscuit joint, a lap joint, a double lap joint, a dovetail joint, or asplice joint. Consequently, joining regions 16 a and 16 b may have anycorresponding geometries to define the surfaces of the joint region. Forexample, for a mortise and tenon joint, first component 12 a may definea mortise (a cavity) and second component 12 b may define a tenon (aprojection that inserts into the mortise). As another example, for asplice joint, first component 12 a may define a half lap, a bevel lap,or the like, and second component 12 b may define a complementary halflap bevel lap, or the like.

In some examples, although not shown in FIG. 1A, assembly 10 may includea clamp, press, or other mechanism for exerting pressure between joiningregions 16 a and 16 b during joining. The pressure between joiningregions 16 a and 16 b may facilitate formation of the joint, e.g., byhelping to at least one of maintain a gap at the joint region, topromote flow or migration of braze material 14, and to evacuate anygases or porosity in braze material 14, which may reduce porosity in thejoint.

FIG. 1B is a conceptual and schematic diagram illustrating a partialview of an example system 20 including assembly 10 of FIG. 1A in afurnace 22. Assembly 10 may be assembled as shown in FIG. 1B, with brazematerial 14 disposed in a joint region 15 defined by joint surfaces 18 aand 18 b of joining regions 16 a and 16 b. In some examples, brazematerial 14 may include a wide gap braze material. For example, brazematerial 14 may include a powder mixture that has been sintered to forma pre-sintered preform (PSP). Sintering may reduce porosity compared tothe powder, which may reduce porosity in joint region 15 during andafter formation of the mechanical interlock. While a single joint region15 is shown in the example assembly of FIG. 1B, in other examples,components 12 a and 12 b may define a plurality of respective jointregions, and braze material 14 may be introduced into respective jointregions of the plurality of joint regions. In some examples, differentcompositions of braze material 14 may be introduced into different jointregions, or in different portions of the same joint region.

In some examples, braze material 14 may include a Ni-based or Co-basedwide gap braze alloy. Braze material 14 may include greater amounts ofalloying elements that some other braze materials used in braze foils,which may contribute to improved mechanical properties, chemicalproperties, or both compared to some other braze materials used in brazefoils. For example, braze material 14 may possess sufficient mechanicalstrength and high temperature oxidation resistance to be used in anozzle guide vane in a gas turbine engine.

In some examples, braze material 14 may include both a braze alloypowder (a low-melt powder composition) and a superalloy powder (ahigh-melt powder composition). The low-melt alloy powder composition isan alloy, or a mixture of alloys, that substantially melts below a brazeor joining temperature (hence the name “low-melt” or “braze powder”). Incontrast, the high-melt alloy powder composition is an alloy, or amixture of alloys, that remains substantially unmelted at the brazetemperature, because the composition has a melting temperature above thebraze temperature (hence the name “high-melt” or “superalloy powder”).In some implementations, the braze alloy powder and the superalloypowder may have specific powder mesh sizes, and may be produced byinduction melting the braze alloy or the superalloy powder,respectively, in vacuum or an argon atmosphere, followed by argon gasatomization. Each individual powder component used in braze material 14may be analyzed to confirm the particle size and chemical compositions.

In some examples, the low-melt powder composition includes an alloy or amixture of alloys that melt at a temperature below about 1260° C. (about2300° F.). The high-melt alloy powder composition may include a singlehigh-melt alloy or a mixture of alloys that melts at a temperature ofgreater than about 1315° C. (about 2400° F.).

In some examples, the low-melt powder composition may include one ormore alloy powders and includes between about 50 wt. % and about 70 wt.% Ni, between about 8 wt. % and about 20 wt. % Cr, between about 8 wt. %and about 15 wt. % Ta, between about 4 wt. % and about 10 wt. % Co,between about 2 wt. % and about 7 wt. % Al, up to about 2.25 wt. % B,and up to about 2.25 wt. % Si, and has a compositional melting range ofbetween about 1093° C. (about 2000° F.) and about 1204° C. (about 2200°F.). In some examples, the low-melt powder composition also includes upto about 1 wt. % each of at least one of Ti, W, Mo, Re, Nb, Hf, Pd, Pt,Ir, Ru, C, Si, P, Fe, Ce, La, Y, or Zr. In some examples the low-meltalloy powder comprises a mixture of two or more low-melt alloys. Forexample, a low-melt alloy powder may include (a) about 35% of a firstlow-melt powder including about 74 wt. % Ni, about 6 wt. % Cr, about 6wt. % Al, about 12 wt. % Co, and about 2 wt. % B, with a liquidustemperature of about 1121° C. (about 2050° F.); (b) about 45% of asecond low-melt powder including about 42 wt. % Ni, about 31 wt. % Cr,about 26 wt. % Ta, and about 1 wt. % B, with a liquidus temperature ofabout 1232° C. (about 2250° F.); and (c) about 20 wt. % of a thirdlow-melt powder including about 64 wt. % Ni, about 6 wt. % Al, about 8wt. % Co, about 4 wt. % W, about 4 wt. % Ta, about 3 wt. % Si, about 1wt. % Re, about 1 wt. % Nb, and about 1 wt. % B, with a liquidustemperature of about 1093° C. (about 2000° F.).

In some examples, the high-melt powder composition may include an alloyor mixture of alloys with a chemistry that is the similar to orsubstantially the same (e.g., the same or nearly the same) as the alloyin first component 12, second component 14, or both. For example, insome implementations, to join a first component 12 and a secondcomponent 14 that include Ni-based superalloy components such as thosemade of MAR-M246 or 247, or CMSX-3 or -4, the high-melt powdercomposition may include between about 50 wt. % and about 70 wt. % Ni,between about 2 wt. % and about 10 wt. % Cr, between about 2 wt. % andabout 10 wt. % Ta, between about 5 wt. % and about 15 wt. % Co, betweenabout 2 wt. % and about 10 wt. % Al, between about 2 wt. % and about 10wt. % W, between about 2 wt. % and about 4 wt. % Re, up to about 3 wt. %Mo, and up to about 3 wt. % Hf. In some examples, the high-melt powdercomposition also may include up to about 1 wt. % each of at least one ofTi, Nb, C, B, Si, or Zr. In some examples, the high-melt powdercomposition includes between about 55 wt. % and about 60 wt. % Ni, about7 wt. % Cr, about 6 wt. % Ta, about 12 wt. % Co, about 6 wt. % Al, about3 wt. % Re, about 1.5 wt. % Hf, and about 5 wt. % W.

The low-melt powder composition and the high-melt powder composition maybe combined in any selected ratio. In some examples, braze material 14may include a powder mixture consisting of between about 20 wt. % andabout 80 wt. % low-melt powder composition and a balance high-meltpowder composition (a ratio of between about 1:4 and about 4:1low-melt:high-melt powder). In some cases, braze alloy powder may be amixture of more than one braze alloys which are all powder. In someexamples, the ratio may be between about 1:3 and about 3:1low-melt:high-melt powder, such as a ratio between about 1:2 and about2:1 low-melt:high-melt powder, or a ratio between about 1:1 and about1:1.5 low-melt:high-melt powder. For example, braze material 14 mayinclude between about 40 wt. % and about 50 wt. % low-melt alloy powderand between about 50 wt. % and about 60 wt. % high-melt powder, such asabout 45 wt. % low-melt alloy powder and about 55 wt. % high-meltpowder.

Hence, in some examples, braze material 14 may include between about 50wt. % and about 90 wt. % Ni, up to about 15 wt. % Cr, up to about 10 wt.% Ta, up to about 10 wt. % Co, up to about 7 wt. % Al, up to about 4 wt.% W, up to about 2 wt. % Re, up to about 1 wt. % Mo, up to about 1 wt. %Hf, and, optionally, up to about 0.5 wt. % Nb, up to about 3 wt. % Si,and up to about 3 wt. % B. In some examples, braze material 14 mayinclude between about 50 wt. % and about 70 wt. % Ni, between about 10wt. % and about 15 wt. % Cr, between about 8 wt. % and about 10 wt. %Ta, between about 8 wt. % and about 10 wt. % Co, between about 4 wt. %and about 7 wt. % Al, between about 2 wt. % and about 4 wt. % W, betweenabout 1 wt. % and about 2 wt. % Re, about 1 wt. % Mo, about 1 wt. % Hf,and, optionally, up to about 1% each at least one of Ti, Nb, Pd, Pt, Ir,Ru, C, B, Si, P, Mn, Fe, Ce, La, Y, or Zr. In some examples, brazematerial 14 may include between about 50 wt. % and about 70 wt. % Ni,between about 10 wt. % and about 15 wt. % Cr, between about 8 wt. % andabout 10 wt. % Ta, between about 8 wt. % and about 10 wt. % Co, betweenabout 4 wt. % and about 7 wt. % Al, between about 2 wt. % and about 4wt. % W, between about 1 wt. % and about 2 wt. % Re, between about 0.5wt. % and about 1 wt. % Mo, between about 0.5 wt. % and about 1 wt. %Hf, between about 0.1 wt. % and about 0.5 wt. % Nb, between about 0.05wt. % and about 3 wt. % Si, and between about 0.5 wt. % and about 2 wt.% B. In some examples, braze material 14 may include about 58 wt. % Ni,about 11 wt. % Cr, about 9 wt. % Ta, about 9 wt. % Co, about 5 wt. % Al,about 3 wt. % W, about 1 wt. % Mo, about 1 wt. % Re, and about 1 wt. %Hf; or may include between about 10.2 wt. % and about 11.3 wt. % Cr,between about 4.8 wt. % and about 5.1 wt. % Al, between about 9.1 wt. %and about 9.8 wt. % Co, between about 2.8 wt. % and about 3.3 wt. % W,between about 0.7 wt. % and about 0.9 wt. % Mo, between about 8.2 wt. %and about 8.8 wt. % Ta, between about 0.6 wt. % and about 0.8 wt. % B,about 0.3 wt. % Si, between about 1.5 wt. % and about 1.8 wt. % Re,between about 0.8 wt. % and about 0.9 wt. % Hf, between about 0.1 wt. %and about 0.2 wt. % Nb, and a balance Ni.

In selecting the proportions of components used in braze material 14,higher weight percentages of high-melt powder may provide bettermechanical properties in view of their reduced levels of melting pointdepressants such as boron, silicon, or both. Conversely, higherpercentages of low-melt powders that include higher levels of meltingpoint depressants such as boron, silicon, or both may provide improvedbraze flow. A proper balance between mechanical properties and brazeflow should be selected, for example, to promote flow of the brazematerial to ultimately at least partially conform to joint region 15,while yet retaining sufficient strength or rigidity to mechanicallysecure components 12 a and 12 b relative to each other.

In some examples, the sintered powder may then be cut or machined into apredetermined shape. For example, the predetermined shape may correspondto a shape of joint region 15. As described above, joint region 15 mayinclude a relatively simple geometry as shown in FIG. 1A, or may includea more complex geometry, e.g., multiple planes or surfaces, simple orcomplex curves, overhangs, undercuts, internal cavities, or the like.Accordingly, the sintered powder may be cut or machined into arelatively simple shape, or a more complex, e.g., including curvature,angles, apertures, or the like to form braze material 14. Regardless ofthe complexity of the shape of PSP material 14 and depending upon thegeometry of joint region 15, braze material 14 may include asubstantially two-dimensional shape (e.g., a plane) or athree-dimensional shape (e.g., including curvature, planes at angleswith respect to one another, and the like). In some examples, brazematerial 14 may include one or more of a putty, a paste, a sheet, astrip, or a pre-molded shape, or a pre-sintered preform, wherein thepre-molded shape at least partially conforms to the joint region. Byutilizing braze material 14, alloys with desirable mechanical andchemical (e.g., high temperature oxidation resistance) may be utilizedin a joining technique to join first component 12 a and second component12 b.

For example, furnace 22 may be used to heat braze material 14 to apredetermined processing temperature to form an at least softenedmaterial (for example, a material that is relatively softer than brazematerial 14, or a partially, substantially, or completely meltedmaterial, or a flowable material). Furnace 22 may include a combustion,infrared, electric, induction, or any suitable source of thermal energy.In some examples, furnace 22 may include a furnace, for example, avacuum furnace. While furnace 22 may be used to heat braze material 14,in some examples, furnace 22 may not be used, and instead, a differentsource of thermal energy may be used to heat braze material 14, forexample, an external heat source. The at least softened material mayflow, migrate, or otherwise at least partially occupy joint region 15,and on cooling, form a mechanical interlock in joint region 15.

FIG. 1C is a conceptual and schematic diagram illustrating a partialsectional and exploded view of region A of system 20 of FIG. 1B. Anadhesion resistant material may be present in joint region 15 between ajoint surface defined by joint region 15 and braze material 14. Forexample, a joint surface defined by joint region 15, for example, asurface of one or both of first or second joining regions 16 a or 16 b,may be coated with an adhesion resistant coating. One or both of jointsurfaces 18 a or 18 b of joint region 15 may be respectively coated withadhesion resistant coating 19 a or 19 b. In some examples, adhesionresistant coating 19 a and 19 b may have the same compositions. In otherexamples, adhesion resistant coating 19 a and 19 b may have differingcompositions. In some examples, one or both of adhesion resistantcoatings 19 a or 19 b (collectively referred to as adhesion resistantcoating 19) may include at least one of an oxidation resistant coatingor a corrosion resistant coating. In some examples, an oxidationresistant coating may itself be a corrosion resistant coating. In someexamples, at least a portion of adhesion resistant coating 19 mayinclude an aluminide coating, for example, a platinum aluminide coating.In some examples, adhesion resistant coating 19 may include at least onenonreactive oxide. For example, the nonreactive oxide may besubstantially nonreactive with respect to braze material 14. At least aportion of adhesion resistant coating 19 may act as a leave-in-place“stop-off”, substantially preventing braze material 14 (or the at leastsoftened material formed by heating braze material 14, or the mechanicalinterlock formed by cooling the at least softened material) fromadhering to surfaces defined by joint region 15, for example, jointsurfaces 18 a and 18 b. In some examples, adhesion resistant coating 19present before, during, and after forming the joint avoids orsubstantially prevents introducing a gap (as contrasted with a stop-offremoved after application). Thus, adhesion resistant coating 19 mayresult in a line-on-line fit or connection between components 12 a and12 b and the mechanical interlock ultimately formed from braze material14, without allowing braze material 14 to form a metallurgical bond orbraze joint with components 12 a and 12 b.

While adhesion resistant coating 19 resists adherence or metallurgicalbonding of the mechanical interlock formed from brazing material 14 tosurfaces of joint region 15, the mechanical interlock still securesfirst component 12 a to second component 12 b or restrains firstcomponent 12 a relative to second component 12 b. For example, the shapeand geometry of the mechanical interlock (for example, substantiallyconforming to joint region 15) may mechanically lock or secure a portionof first component 12 a relative to a respective portion of secondcomponent 12 b. In some examples, the mechanical interlock at leastpartially surrounds at least one of first component 12 a or secondcomponent 12 b. For example, the mechanical interlock may surround aperimeter subtending an angle greater than 180°, or greater than 210°,or greater than 240°, or greater than 270°, or greater than 300°, orsubstantially 360° (for example, within 1°, 5°, or 10° of 360°) about acentral axis defined respectively by first component 12 a or secondcomponent 12 b. In some examples, the mechanical interlock may form aring, or a sleeve, surrounding one or both of components 12 a or 12 b.In some examples, the mechanical interlock may be exterior to anexterior surface defined by one of components 12 a or 12 b, and interiorto an interior surface defined by the other of components 12 a or 12 b.For example, in the examples shown in FIGS. 1A, 1B, and 1C, brazematerial 14 (and the mechanical interlock ultimately formed from brazematerial 14) surrounds and is exterior to (radially outward of) secondcomponent 12 b, while being interior to (radially inward of) firstcomponent 12 a. However, any suitable configuration of braze material 14relative to components 12 a and 12 b that secures components 12 a and 12b together may be used.

The mechanical interlock ultimately formed from braze material 14 maypossess sufficient mechanical strength and high temperature oxidationresistance to be utilized in a high temperature mechanical system, suchas a nozzle guide vane in a gas turbine engine. Further, by utilizing aPSP in some examples, the joint may include reduced porosity compared toa joint formed using a braze powder, and positioning of a PSP may beeasier and more precise than with a braze powder. In this way, a PSP mayfacilitate the formation of an article from multiple, smallercomponents, easing or reducing the cost of forming the article.

Thus, braze material 14 can be formed into structures or otherwiseintroduced into joint region 15, while having the ability to changeshape or “morph” during a high temperature furnace operation from apliable or ductile green state (or even a semi-rigid state whenpre-sintered) into a state that further softens and has the ability tosubstantially conform to the shape of joint region 15 or a cavity orchannel in which braze material 14 is placed. Such deforming of brazematerial 14 may be accomplished at a temperature well below the meltingpoint of components 12 a or 12 b, for example, without braze material 14itself melting into a full liquid state (in contrast with bi-casting,which may require a liquid molten state). However, in other examples,while braze material 14 may be molten or heated to a liquid state,components 12 a or 12 b themselves may be maintained in a solid state,retaining the integrity of components 12 a and 12 b. In some examples,as described elsewhere in the disclosure, braze material 14 may beformed into multiple sections placed adjacent to each other in jointregion 15. In such a configuration, the multiple sections will securelybond and fuse to each other during a high temperature furnace operation.

In some examples, the melting characteristics of braze material 14 maychange in response to high temperature exposure. For example, brazematerial 14 may include a relatively small percentage of a low meltingcomponent, for example, brazing powder, and a relatively higherpercentage of a high melting component, for example, superalloy. The lowmelting component may include an alloy additive that depresses themelting point of the low melting component, causing the low meltingcomponent to liquefy at this lower temperature, causing braze material14 to soften and slip (and unite if more than one strip is used) duringthe furnace operation. However, the alloy addition that depresses themelting point of the low melting component may diffuse during thefurnace operation (or during a post-furnace diffusion heat treatment)into the larger volume of high melting component, for example,superalloy. Such diffusion may raise the re-melt temperature of themechanical interlock ultimately formed from braze material 14, such thatthe mechanical interlock (morphed and fused) material formed from brazematerial 14 transforms into a rigid metallic structure, (for example a“ring”) after the furnace operation and when in subsequent use at hightemperature operating conditions.

Thus, after the completion of the thermal cycle (and after an optionaldiffusion heat treat cycle) braze material 14 may transform into anintegrally shaped and consolidated mechanical interlock (in someexamples, a “ring”) trapped in cavities or channels bridging betweencomponents 12 a and 12 b. The mechanical interlock formed from brazematerial 14 may thus function as a high strength, high temperaturecapable (closely conforming) structural member with material propertiessimilar to a high temperature superalloy, for example, superalloyconstituent(s) used in the formulation of braze material 14.

FIG. 2 is a flow diagram illustrating an example technique for joiningcomponents 12 a and 12 b using braze material 14. The technique of FIG.2 will be described with reference to assembly 10 of FIGS. 1A, 1B, and1C for purposes of illustration only. It will be appreciated that thetechnique of FIG. 2 may be performed with a different assembly orsystem, or that assembly 10 may be used in a different joiningtechnique.

In some examples, the example technique of FIG. 2 includes optionallycoating a joint surface of joint region 15 defined by first and secondcomponents 12 a and 12 b with adhesion resistant coating 19 (30). Thecoating technique may include physical vapor deposition, chemical vapordeposition, plasma deposition, spraying, deposition of a liquid, marker,or putty, atmospheric exposure at high temperatures, or any othersuitable coating technique. In some examples, the example technique maynot include the coating step (30), and instead, pre-coated components 12a and 12 b may be used. The coating (30) may be performed prior topositioning braze material 14 in joint region 15. In some examples, thetechnique of FIG. 2 may include positioning at least one adhesionresistant material within joint region 15, e.g., between braze material14 and joint surfaces 18 a and 18 b, in addition to or instead ofcoating a joint surface of joint region 15 defined by first and secondcomponents 12 a and 12 b with adhesion resistant coating 19 (30).

Although not shown in FIG. 2 , in some examples, joint surfaces 18 a and18 b of components 12 a and 12 b, respectively, may be inspected andcleaned, for example, before the coating (30), after the coating (30),or before the positioning (32). The cleaned joint surfaces 18 a and 18 bmay produce a more uniform joint than uncleaned joint surfaces.

The technique of FIG. 2 includes positioning components 12 a and 12 b todefine joint region 15 (32). For example, as shown in FIGS. 1B and 1C,components 12 a and 12 b may be positioned so that joining regions 16 aand 16 b are near each other. As described elsewhere in the disclosure,the geometry of joint region 15 may depend on the type of joint definedby joint surfaces 18 a and 18 b and may include, for example, a bridlejoint, a butt joint, a scarf joint, a miter join, a dado joint, a groovejoint, a tongue and groove joint, a mortise and tenon joint, abirdsmouth joint, a halved joint, a biscuit joint, a lap joint, a doublelap joint, a dovetail joint, or a splice joint.

In some examples, the example technique of FIG. 2 optionally includespre-molding braze material 14 to at least partially conform to jointregion 15 (34), e.g., in examples in which braze material 14 includes aPSP. For example, the molding (34) may include stamping, cutting,rolling, pressing, imprinting, or otherwise molding braze material 14 ina mold to provide a predetermined shape to braze material 14. In someexamples, the molding (34) may include preparing strips, sheets, tubes,tapes, or any suitable shapes from braze material 14. In some examples,braze material 14 may be molded into a unitary pre-molded shape, forexample, a continuous shape. In other examples, braze material 14 may bemolded into discrete shapes, for example, having different shapes orsizes. As joint region 15 may include a relatively simple geometry or amore complex geometry, braze material 14 may be cut or machined into arelatively simple shape, or a more complex shape, e.g., includingcurvature, angles, apertures, or the like. Different surfaces of thesame piece or different pieces of pre-molded braze material 14 mayconform to respective different surfaces at least partially defined byjoint region 15. In some examples, the example technique may not includethe pre-molding (34), and instead, no particular initial shape or formmay be provided to braze material 14.

The technique of FIG. 2 also includes disposing braze material 14 injoint region 15 (36). As described above, braze material 14 may define apredetermined shape that at least partially corresponds to the geometryof joint region 15. Braze material 14 may be disposed in joint region 15such that respective surfaces of braze material 14 contact respectivejoint surfaces of joint region 15, for example, joint surfaces 18 a and18 b. In some examples, the positioning (36) includes introducing asingle piece or unit of braze material 14 into joint region 15. In otherexamples, the positioning may include introducing different pieces ofbraze material 14 into respective predetermined portions of joint region15.

In some examples, the positioning of components 12 a and 12 a (32)occurs prior to the disposing braze material 14 in joint region 15 (36).In some such examples, braze material 14 may be introduced into jointregion 15 through or via an opening defined by joint region 15, forexample, opening 11 shown in FIG. 1B. In other examples, the positioningof components 12 a and 12 a (32) occurs after braze material 14 isdisposed within part of joint region 15 (36). For example, a portion ofPSP material 14 may be placed in contact with or secured into a portionof one of joint surfaces 18 a or 18 b, followed by the positioning (32)of components 12 a and 12 b to resulting in bringing the other of jointsurfaces 18 a or 18 b in contact with PSP material 14. In some examples,a first portion of braze material 14 may be introduced into joint region15 (or portion of a component defining a portion of joint region 15)before the positioning of components 12 a and 12 a (32), and a secondportion of braze material 14 may be introduced into joint region 15 (orportion of a component defining a portion of joint region 15) after thepositioning (32). In some examples, a clamp, press, or other mechanismmay be used to compress braze material 14 between joint regions 16 a and16 b to cause intimate contact between joint surfaces 18 a and 18 b andsurfaces of braze material 14, although intimate contact between jointsurfaces 18 a and 18 b and surfaces of braze material 14 is notrequired, since no metallurgical bond is formed between braze material14 and joint surfaces 18 a and 18 b.

The technique of FIG. 2 further includes heating braze material 14 to aprocessing temperature to melt or soften at least part of braze material14 (38). In some examples, braze material 14 may be heated in a furnaceor a closed retort, and components 12 a and 12 b may be heated withbraze material 14. In some examples, the furnace or closed retort mayenclose a vacuum or substantially inert atmosphere (e.g., an atmosphereincluding constituents that substantially do not react with components12 a and 12 b and braze material 14 at the temperatures and pressuresexperienced by the interior of the furnace or closed retort). In someexamples, braze material 14 may be heated by a local heat source, forexample, a laser, an e-beam, or any suitable directed energy source thatmay heat braze material 14 without substantially heating components 12 aor 12 b.

Regardless of the heat treatment used for melting or softening at leasta portion of braze material 14 (38), braze material 14 may be allowed tocool to ambient temperature to form a solid (for example, the mechanicalinterlock) and join components 12 a and 12 b (39). The cooling of brazematerial 14 (39) may include one or both of active cooling, where forcedconvection, or conduction by contact with a relatively cooler medium maybe used to ultimately draw away heat from braze material 14 or passivecooling, where braze material 14 may be allowed to cool by releasingheat to the ambient environment and components 12 a and 12 b. Inexamples in which assembly 10 is heated in furnace 22, assembly 10 maybe removed from furnace 22 before cooling braze material 14 (39).

Thus, the example technique of FIG. 2 may be used to form a mechanicalinterlock between components 12 a and 12 b from braze material 14 inassembly 10 of FIGS. 1A, 1B, and 1C, without forming a metallurgicalbond between components 12 a and 12 b. Although FIG. 1A illustrates asimplified conceptual and schematic view of an example first component12 a, an example second component 12 a, and an example braze material14, in other examples, example assemblies may include components andbraze material 14 defining a more complication geometry, for example, asdescribed with reference to FIG. 3A to 8. The example technique of FIG.2 may be used to process any example assemblies according to thedisclosure to form mechanical interlocks between components.

For example, FIG. 3A is a conceptual and schematic diagram illustratingan exploded cross-sectional view of an example assembly 40 includingcomponents (42 a, 42 b, and 42 c) and braze material (44 a and 44 b)between components 42 a, 42 b, and 42 c. FIG. 3B is a conceptual andschematic diagram illustrating an assembled cross-sectional view ofassembly 40 of FIG. 3A. FIG. 3C is a conceptual and schematic diagramillustrating a partial cross-sectional view of region C of assembly 40of FIG. 3B. In FIG. 3C, braze material 44 a is removed to show a jointregion 45 defined by components 42 a and 42 b.

In the example illustrated in FIG. 3A, component 42 a of assembly 40defines a nozzle guide vane (NGV) for a gas turbine engine, component 42b defines an airfoil, and component 42 c defines a platform. Each ofcomponents 42 a, 42 b, or 42 c may be formed of a metal or alloy, suchas a Ni- or Co-based superalloy, or include a ceramic-based structure,for example, a ceramic-matrix composite. Further, components 42 a, 42 b,or 42 c may be formed of the same metal or alloy, or of different metalsor alloys, or ceramics. In the example shown in FIGS. 3A, 3B, and 3C,component 42 a surrounds an exterior of component 42 b, and joint region45 in FIG. 3C surrounds component 42 b. Thus, joint region 45 includesboth channels or voids shown in the left and right portions of FIG. 3C.Similarly, joint region 45 defines a continuous opening 47 surroundingcomponent 42 b. For example, joint region 45 may follow a perimeter ofan airfoil blade, or any predetermined path.

As shown in FIG. 3B, the joint region between components 42 a and 42 bis occupied by braze material 44 a, and the joint region betweencomponents 42 b and 42 c is occupied by braze material 44 b. Thus,components 42 a, 42 b, and 42 c possess a more complex geometry thanthat shown in FIGS. 1A to 1C. Braze materials 44 a and 44 b accordinglyinclude a more complex geometry, shaped to substantially conform to thegeometry of the respective joint regions in which braze materials 44 aand 44 b are positioned. Upon completion of the joining technique, amechanical interlock formed from braze material 44 a mechanicallyrestrains components 42 a and 42 b relative to each other, and amechanical interlock formed from braze material 44 b mechanicallyrestrains components 42 b and 42 c relative to each other. Themechanical interlock surrounds component 42 b. In this way, brazematerials 44 a and 44 b are used to mechanically join three components42 a, 42 b, and 42 c, to form an assembly 40 with a more complexgeometry, without forming metallurgical bonds between the respectivecomponents 42 a, 42 b, and 42 c. This may reduce manufacturing time andcost compared to forming assembly 40 from a single casting.

FIG. 4 is a conceptual and schematic diagram illustrating a partialcross-sectional view of an example assembly 50 including components 52 aand 52 b and defining a joint region 55 for forming a mechanicalinterlock. Components 52 a and 52 b may be substantially similar tocomponents 42 a and 42 b described with reference to FIG. 3 . However,in some examples, components 52 a and 52 b define a conical sealinterface 58. For example, conical seal interface 58 may be definedbetween components 52 a and 52 b proximate to and outside of jointregion 55. Conical seal interface 58 may provide an alternate load pathindependent from the joint for supporting an inward load betweencomponents 42 a and 42 b. Such an inward load may be a result ofoperating conditions of components 42 a and 42 b, for example, duringengine operation. In contrast with components that no not define such aconical seal interface, providing conical seal interface 58 may allowfor modified machining of joint region 55. For example, while FIGS. 3and 4 are not uniformly drawn to scale, and distances may be exaggeratedfor illustration, joint region 55 of assembly 50 may be provided with anopening 57 as shown in FIG. 4 that is relatively wider than opening 47of joint region 45 of assembly 40 shown in FIG. 3C (below) becauseinward loading is being supported by conical seal interface 58.

Such a relatively wider opening may provide a “trench” to expose partialaccess to joint region 57 for installing braze material in joint region55 surrounding component 52 b. Braze material may be introduced throughopening 57 into joint region 55 in one or more forms or states, asdescribed with reference to FIGS. 5 to 8 , for example, a paste, putty,strips, pre-molded shape, or a pre-sintered preform (PSP).

FIG. 5 is a conceptual and schematic diagram illustrating a partialcross-sectional view of example assembly 50 a including components 52 aand 52 and braze paste 54 a. Assembly 50 a is substantially similar toassembly 50 of FIG. 4 , with braze paste 54 a introduced into jointregion 55. Braze paste 54 a may include components similar to brazematerial 14 or other braze material described elsewhere in thedisclosure. Braze paste 54 a may additionally include optionalcomponents, for example, a carrier, a plasticizer, a softener, or abinder, to promote the formation of a paste. Using braze paste 54 a asopposed to solid or powdered braze material may allow braze material tobe introduced precisely into joint region 55 without creating powder orother waste, and may allow controlled introduction, for example, byextrusion from a nozzle, or otherwise being pressed or pushed introjoint region 55. Upon heating, braze paste 54 a may flow, deform,migrate, or otherwise form an at least softened material that at leastpartly conforms to joint region 55, and upon cooling, form a mechanicalinterlock in joint region 55. The mechanical interlock mechanicallyrestrains components 52 a and 52 b relative to each other. In someexamples, the mechanical interlock formed from braze paste 54 a at leastpartially surrounds component 52 b. In some examples, the mechanicalinterlock substantially surrounds component 52 b, securing component 52a to 52 b about component 52 in the region adjacent joint region 55. Inthis way, braze paste 54 a is used to mechanically join components 52 aand 52 b to form assembly 50 a with a more complex geometry, withoutforming metallurgical bonds between the respective components 52 a and52 b. This may reduce manufacturing time and cost compared to formingassembly 50 a from a single casting.

FIG. 6 is a conceptual and schematic diagram illustrating a partialcross-sectional view of an example assembly 60 including components 52 aand 52 b and braze putty 54 b. Assembly 60 is substantially similar toassembly 50 of FIG. 4 , with braze putty 54 b introduced into jointregion 55. Braze putty 54 b may include components similar to brazematerial 14 or other braze material described elsewhere in thedisclosure. Braze putty 54 b may additionally include optionalcomponents, for example, a carrier, a plasticizer, a softener, or abinder, to promote the formation of a putty. Using braze putty 54 b asopposed to solid or powdered braze material may allow braze material tobe introduced precisely into joint region 55 without creating powder orother waste, and may allow controlled introduction, for example, byextrusion from a nozzle, or otherwise being pressed or pushed introjoint region 55. braze putty 54 b may include more than one piece, forexample, as shown in FIG. 6 . Using multiple pieces of braze putty 54 bmay allow easier introduction of putty 54 b into joint region 55. Uponheating, braze putty 54 b may flow, deform, migrate, or otherwise forman at least softened material that at least partly conforms to jointregion 55, and upon cooling, form a mechanical interlock in joint region55. The mechanical interlock mechanically restrains components 52 a and52 b relative to each other. In some examples, the mechanical interlockformed from braze putty 54 b at least partially surrounds component 52b. In some examples, the mechanical interlock substantially surroundscomponent 52 b, securing component 52 a to 52 b about component 52 inthe region adjacent joint region 55. In this way, braze putty 54 b isused to mechanically join components 52 a and 52 b to form assembly 60with a more complex geometry, without forming metallurgical bondsbetween the respective components 52 a and 52 b. This may reducemanufacturing time and cost compared to forming assembly 60 from asingle casting.

FIG. 7 is a conceptual and schematic diagram illustrating a partialcross-sectional view of an example assembly 70 including components 52 aand 52 b and pre-sintered preform (PSP) strips 54 c including brazematerial. Assembly 70 is substantially similar to assembly 50 of FIG. 4, with PSP strips 54 c introduced into joint region 55. PSP strips 54 cmay include components similar to PSP material 14 or other PSP materialdescribed elsewhere in the disclosure. In some examples, PSP strips 54 cmay allow substantially plastic deformation, substantially retainingdeformed shape. For example, if PSP strips 54 c are bent into a circle,ellipse, or any predetermined curve, PSP strips 54 c may substantiallyretain the predetermined deformed shape. Using PSP strips 54 c asopposed to conventional braze material may allow PSP material to beintroduced rapidly and precisely into joint region 55 without creatingpowder or other waste, and may allow controlled introduction, forexample, by a pick-and-place operation, or otherwise being pressed orpushed intro joint region 55. PSP strips 54 c may include more than onepiece, for example, as shown in FIG. 7 . Using multiple pieces of PSPstrips 54 c may allow easier introduction of PSP strips 54 c into jointregion 55. Upon heating, PSP strips 54 c may flow, deform, migrate, orotherwise form an at least softened material that at least partlyconforms to joint region 55, and upon cooling, form a mechanicalinterlock in joint region 55. In some examples, the at least softenedmaterial from different pieces of PSP strips 54 c may merge into acohesive or unitary softened material. The mechanical interlockmechanically restrains components 52 a and 52 b relative to each other.In some examples, the mechanical interlock formed from PSP strips 54 cat least partially surrounds component 52 b. In some examples, themechanical interlock substantially surrounds component 52 b, securingcomponent 52 a to 52 b about component 52 in the region adjacent jointregion 55. In this way, PSP strips 54 c are used to mechanically joincomponents 52 a and 52 b to form assembly 70 with a more complexgeometry, without forming metallurgical bonds between the respectivecomponents 52 a and 52 b. This may reduce manufacturing time and costcompared to forming assembly 70 from a single casting.

FIG. 8 is a conceptual and schematic diagram illustrating a partialcross-sectional view of an example assembly 80 including components 52 aand 52 b and pre-molded pre-sintered preform (PSP) strips 54 d includingbraze material. Assembly 80 is substantially similar to assembly 50 ofFIG. 4 , with pre-molded PSP strips 54 d introduced into joint region55. Pre-molded PSP strips 54 d may relatively conform better to jointregion 55, requiring a lower extent or degree of flow or migration toeventually form a mechanical interlock in joint region 55. In someexamples, pre-molded PSP strips 54 d may have a shape and geometry thatpermits introduction of pre-molded PSP strips 54 d through opening 57without substantially changing the conformance of pre-molded PSP strips54 d. In some such examples, pre-molded PSP strips 54 d may beintroduced into joint region 55 through opening 57. In other examples,pre-molded PSP strips 54 d may not have a geometry or shape permittingintroduction through opening 57. In some examples, pre-molded PSP strips54 d may be first fitted or (at least temporarily) secured in contactwith or within one of components 52 a or 52 b, and then the other ofcomponents 52 a or 52 b may be positioned adjacent the other ofcomponents 52 a or 52 b such that pre-molded PSP strips are ultimatelydisposed in joint region 55. Pre-molded PSP strips 54 d may includecomponents similar to PSP material 14 or other PSP material describedelsewhere in the disclosure. In some examples, pre-molded PSP strips 54d may allow substantially plastic deformation, substantially retainingdeformed shape. For example, if pre-molded PSP strips 54 d are bent intoa circle, ellipse, or any predetermined curve, pre-molded PSP strips 54d may substantially retain the predetermined deformed shape. Usingpre-molded PSP strips 54 d as opposed to conventional braze material mayallow PSP material to be introduced rapidly and precisely into jointregion 55 without creating powder or other waste, and may allowcontrolled introduction, for example, by a pick-and-place operation, orotherwise being pressed or pushed intro joint region 55. Pre-molded PSPstrips 54 d may include more than one piece, for example, as shown inFIG. 8 . Using multiple pieces of PSP strips 54 c may allow easierintroduction of pre-molded strips 54 d into joint region 55. Uponheating, pre-molded PSP strips 54 d may flow, deform, migrate, orotherwise form an at least softened material that at least partlyconforms to joint region 55, and upon cooling, form a mechanicalinterlock in joint region 55. In some examples, the at least softenedmaterial from different pieces of pre-molded PSP strips 54 d may mergeinto a cohesive or unitary softened material. In some examples, themechanical interlock formed from pre-molded PSP strips 54 d at leastpartially surrounds component 52 b. The mechanical interlockmechanically restrains components 52 a and 52 b relative to each other.In some examples, the mechanical interlock substantially surroundscomponent 52 b, securing component 52 a to 52 b about component 52 inthe region adjacent joint region 55. In this way, pre-molded PSP strips54 d are used to mechanically join components 52 a and 52 b to formassembly 80 with a more complex geometry, without forming metallurgicalbonds between the respective components 52 a and 52 b. This may reducemanufacturing time and cost compared to forming assembly 80 from asingle casting.

Thus, a mechanical interlock formed from braze material may be used tomechanically join components having relatively complex geometries anddefining relatively complex joint regions without forming metallurgicalbonds with the components.

In some examples, instead of or in addition to using an adhesionresistant coating to prevent metallurgical bonding between a brazematerial and adjacent components, a superalloy foil or powder may beused as an adhesion resistant material. The superalloy foil or powdermay be positioned between the braze material and surfaces of thecomponents to be mechanically joined. The superalloy foil or powder maybe selected to have a melting temperature higher than the processingtemperature to which the braze material is heated, such that thesuperalloy foil or powder does not melt during the formation of themechanical interlock from the braze material. As such, the superalloyfoil or powder forms a physical barrier between the braze material andthe components to prevent a metallurgical bond from forming between thebraze material and the components. FIG. 9A is a conceptual and schematicdiagram illustrating a partial sectional and exploded view of a regionsimilar to region A of system 20 of FIG. 1B.

Assembly 90 of FIG. 9A is similar to assembly 10 of FIGS. 1A-1C exceptfor the differences described herein. For example, like assembly 10,assembly 90 incudes first and second components 12 a and 12 b. Firstcomponent 12 a defines joining region 16 a and joint surface 18 a.Second component 12 b defines joining region 16 b and joint surface 18b. Assembly 90 also includes braze material 14, which may include any ofthe braze materials described herein.

Unlike assembly 10 of FIGS. 1A-1C, assembly 90 includes a superalloyfoil or powder 21 between braze material 14 and joint surfaces 18 a and18 b, and may omit adhesion resistant coating 19 a and/or 19 b.Superalloy foil or powder 21 may include any suitable superalloy, suchas a Ni- or Co-based superalloy. For example, superalloy foil or powder21 may include Ni-based alloys available from Martin-Marietta Corp.,Bethesda, MD, under the trade designation MAR-M246, MAR-M247; Ni-basedalloys available from Cannon-Muskegon Corp., Muskegon, MI, under thetrade designations CMSX-3, CMSX-4, CMSX-10, and CM-186; Co-based alloysavailable from Martin-Marietta Corp., Bethesda, MD, under the tradedesignation MAR-M509; or the like. The superalloy of superalloy foil orpowder 21 may be selected to have a melting temperature that is greaterthan the processing temperature to which braze material 14 is heatedwhen forming the mechanical interlock. In this way, superalloy foil orpowder 21 may act as a physical barrier that prevents metallurgicbonding of braze material 14 to joint surfaces 18 a and 18 b.

In some examples, as shown in FIG. 9A, superalloy foil or powder 21 mayat least partially surround braze material 14. For example, a superalloyfoil may be wrapped around a circumference of braze material 14 or apowder may be disposed (e.g., rolled, sprayed, or dusted) oncircumferential surfaces of braze material 14, as shown in FIG. 9A. Inother examples, superalloy foil or powder 21 may be disposed againstjoint surfaces 18 a and 18 b.

Superalloy foil or braze 21 can be positioned between braze material 14and joint surfaces 18 a and 18 b at any one or more of multiple timesthroughout the joining process of components 12 a and 12 b. Superalloyfoil or braze 21 can be applied, for example, before coating jointsurfaces 18 a and 18 b with an adhesion resistant coating (30), aftercoating joint surfaces 18 a and 18 b with an adhesion resistant coating(30), before positioning first and second components 12 a and 12 badjacent to each other (32), after positioning first and secondcomponents 12 a and 12 b adjacent to each other (32), before positioningbraze material 14 in the joint region (36), or after before positioningbraze material 14 in the joint region (36) in the technique of FIG. 2 .

In some examples, superalloy foil or powder 21 includes a lowerconcentration of melting point depressants, such as silicon or boron,than braze material 14. As such, during heating of braze material 14 toform the mechanical interlock, at least some of the melting pointdepressants, such as silicon or boron, may diffuse into the superalloyfoil or powder 21, reducing the concentration of these species in brazematerial 14. This may raise a melting temperature of braze material 14,improving mechanical properties of the mechanical interlock.

In some examples, an assembly may include a melting point depressantsink in addition to, or instead of, superalloy foil or powder 21. FIG.9B is a conceptual and schematic diagram illustrating a partialsectional and exploded view of a region similar to region A of thesystem of FIG. 1B. Assembly 100 of FIG. 9B is similar to assembly 10 ofFIGS. 1A-1C except for the differences described herein. For example,like assembly 10, assembly 90 incudes first and second components 12 aand 12 b. First component 12 a defines joining region 16 a and jointsurface 18 a. Second component 12 b defines joining region 16 b andjoint surface 18 b. Joint surfaces 18 a and 18 b include adhesionresistant coatings 19 a and 19 b. Assembly 90 also includes brazematerial 14, which may include any of the braze materials describedherein.

Unlike assembly 10, assembly 100 includes a wire 17 embedded in brazematerial 14. Wire 17 may include any suitable superalloy, such as a Ni-or Co-based superalloy. For example, wire 17 may include Ni-based alloysavailable from Martin-Marietta Corp., Bethesda, MD, under the tradedesignation MAR-M246, MAR-M247; Ni-based alloys available fromCannon-Muskegon Corp., Muskegon, MI, under the trade designationsCMSX-3, CMSX-4, CMSX-10, and CM-186; Co-based alloys available fromMartin-Marietta Corp., Bethesda, MD, under the trade designationMAR-M509; or the like. The superalloy of wire 17 may be selected to havea melting temperature that is greater than the processing temperature towhich braze material 14 is heated when forming the mechanical interlock.

Wire 17, as shown in FIG. 9B, has a circular transverse cross-section.However, wire 17 can take any suitable configuration, such asrectangular cross-section (aligned vertically, horizontally, or other tobraze material 14), an elliptical cross-section, or the like. Wire 17can also extend along a length of braze material 14 continuously orintermittently (e.g., at regularly- or irregularly-spaced sections).Further, although assembly 100 includes a single wire 17, an assembly100 may include multiple wires contacting or embedded within brazematerial 14.

Wire 17 may include a lower concentration of melting point depressants,such as silicon or boron, than braze material 14. As such, duringheating of braze material 14 to form the mechanical interlock, at leastsome of the melting point depressants, such as silicon or boron, maydiffuse into the wire 17, reducing the concentration of these species inbraze material 14. This may raise a re-melting temperature of brazematerial 14, improving mechanical properties of the mechanical interlockultimately formed from braze material 14.

Various examples have been described. These and other examples arewithin the scope of the following claims.

1-11. (canceled)
 12. An assembly comprising: a first component; a secondcomponent, wherein the first component and second component arepositioned adj acent to each other to define a j oint region between adjacent portions of the first component and the second component, whereinthe joint region defines a joint surface; a mechanical interlockcomprising braze material disposed in the joint region; and an adhesionresistant material between the braze material and the joint surface,wherein the adhesion resistant material is configured to resistadherence of the braze material to the joint surface, wherein the brazematerial is configured to form an at least softened material in thejoint region in response to heating the braze material to a processingtemperature, and wherein the at least softened material is configured toform the mechanical interlock in the joint region mechanically joiningthe first and second components in response to cooling, and wherein thebraze material is not metallurgically bonded to the first component orthe second component.
 13. The assembly of claim 12, further comprising aheat source configured to heat the braze material in the joint region.14. The assembly of claim 12, wherein the adhesion resistant materialcomprises an adhesion resistant coating on the joint surface, andwherein the adhesion resistant coating comprises at least one of anoxidation resistant coating or a corrosion resistant coating.
 15. Theassembly of claim 12, wherein the adhesion resistant material comprisesat least one of a superalloy foil or a superalloy powder, and whereinthe at least one of the superalloy foil or the superalloy powder isselected to have a melting point above the processing temperature. 16.The assembly of claim 12, wherein the mechanical interlock at leastpartially surrounds at least one of the first component or the secondcomponent to mechanically secure the first component relative to thesecond component.
 17. The assembly of claim 12, wherein the firstcomponent and the second component define an opening in the jointregion, wherein the opening is configured to allow introduction of thebraze material into the joint region.
 18. The assembly of claim 12,wherein the first component and the second component define a conicalseal interface.
 19. The assembly of claim 12, wherein the braze materialcomprises one or more of a putty, a paste, a sheet, a strip, apre-molded shape at least partially conforming to the joint region, or apre-sintered preform having a shape substantially conforming to thejoint region.
 20. The assembly of claim 19, wherein the first componentcomprises a Ni-based or a Co-based superalloy, and wherein the secondcomponent comprises a Ni-based or a Co-based superalloy.
 21. An assemblycomprising: a first component with a first joint surface; a secondcomponent with a second joint surface; a first adhesion resistant layeron the first joint surface, wherein the first adhesion layer comprises afirst material selected to resist adherence of a braze material to thefirst joint surface; a second adhesion resistant layer on the secondjoint surface, wherein the second adhesion layer comprises a secondmaterial selected to resist adherence of a braze material to the secondjoint surface; and a mechanical interlock between the first adhesionresistant layer and the second adhesion resistant layer, wherein themechanical interlock comprises a hardened braze material that ismetallurgically unbound to any of the first adhesion resistant layer,the second adhesion resistant layer, the first j oint surface, and thesecond j oint surface, and wherein the mechanical interlock at leastpartially surrounds at least one of the first component or the secondcomponent to mechanically secure the first component relative to thesecond component.
 22. The assembly of claim 21, wherein first adhesionlayer and the second adhesion layer each comprise at least one of asuperalloy foil or a superalloy powder, and wherein the at least one ofthe superalloy foil or the superalloy powder is selected to have amelting point above a processing temperature of the braze material. 23.The assembly of claim 21, wherein the first component comprises aNi-based or a Co-based superalloy, and wherein the second componentcomprises a Ni-based or a Co-based superalloy.
 24. The assembly of claim21, wherein the braze material comprises one or more of a putty, apaste, a sheet, a strip, a pre-molded shape at least partiallyconforming to a joint region between the first adhesion resistant layerand the second adhesion resistant layer, or a pre-sintered preformhaving a shape substantially conforming to the joint region.
 25. Anassembly comprising: a first component with a first joint surface; asecond component with a second joint surface; a first adhesion resistantlayer on the first joint surface, wherein the first adhesion layercomprises a first material selected to resist adherence of a brazematerial to the first joint surface; a second adhesion resistant layeron the second joint surface, wherein the second adhesion layer comprisesa second material selected to resist adherence of a braze material tothe second joint surface; and a mechanical interlock between the firstadhesion resistant layer and the second adhesion resistant layer,wherein the mechanical interlock is derived from a braze material thatis heated to a processing temperature and softened, and subsequentlycooled to form a hardened braze material, wherein the hardened brazematerial is metallurgically unbound to any of the first adhesionresistant layer, the second adhesion resistant layer, the first j ointsurface, and the second joint surface, and wherein the mechanicalinterlock at least partially surrounds at least one of the firstcomponent or the second component to mechanically secure the firstcomponent relative to the second component.
 26. The assembly of claim25, wherein first adhesion layer and the second adhesion layer eachcomprise at least one of a superalloy foil or a superalloy powder, andwherein the at least one of the superalloy foil or the superalloy powderis selected to have a melting point above a processing temperature ofthe braze material.
 27. The assembly of claim 25, wherein the firstcomponent comprises a Ni-based or a Co-based superalloy, and wherein thesecond component comprises a Ni-based or a Co-based superalloy.
 28. Theassembly of claim 25, wherein the braze material comprises one or moreof a putty, a paste, a sheet, a strip, a pre-molded shape at leastpartially conforming to a joint region between the first adhesionresistant layer and the second adhesion resistant layer, or apre-sintered preform having a shape substantially conforming to thejoint region.